evaluate: expand sets and maps before evaluation

commit 56c90a2dd2eb9cb63a6d74d0f5ce8075bef3895b upstream.

3975430b12d9 ("src: expand table command before evaluation") moved
ruleset expansion before evaluation, except for sets and maps. For
sets and maps there is still a post_expand() phase.

This patch moves sets and map expansion to allocate an independent
CMD_OBJ_SETELEMS command to add elements to named set and maps which is
evaluated, this consolidates the ruleset expansion to happen always
before the evaluation step for all objects, except for anonymous sets
and maps.

This approach avoids an interference with the set interval code which
detects overlaps and merges of adjacents ranges. This set interval
routine uses set->init to maintain a cache of existing elements. Then,
the post_expand() phase incorrectly expands set->init cache and it
triggers a bogus ENOENT errors due to incorrect bytecode (placing
element addition before set creation) in combination with user declared
sets using the flat syntax notation.

Since the evaluation step (coming after the expansion) creates
implicit/anonymous sets and maps, those are not expanded anymore. These
anonymous sets still need to be evaluated from set_evaluate() path and
the netlink bytecode generation path, ie. do_add_set(), needs to deal
with anonymous sets.

Note that, for named sets, do_add_set() does not use set->init. Such
content is part of the existing cache, and the CMD_OBJ_SETELEMS command
is responsible for adding elements to named sets.

Fixes: 3975430b12d9 ("src: expand table command before evaluation")
Reported-by: Jann Haber <jannh@selfnet.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 32 insertions, 40 deletions

diff --git a/src/evaluate.c b/src/evaluate.c
index f7fdc91d..c183832b 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -4363,6 +4363,29 @@ static int set_expr_evaluate_concat(struct eval_ctx *ctx, struct expr **expr)
 	return 0;
 }
 
+static int elems_evaluate(struct eval_ctx *ctx, struct set *set)
+{
+	ctx->set = set;
+	if (set->init != NULL) {
+		__expr_set_context(&ctx->ectx, set->key->dtype,
+				   set->key->byteorder, set->key->len, 0);
+		if (expr_evaluate(ctx, &set->init) < 0)
+			return -1;
+		if (set->init->etype != EXPR_SET)
+			return expr_error(ctx->msgs, set->init, "Set %s: Unexpected initial type %s, missing { }?",
+					  set->handle.set.name, expr_name(set->init));
+	}
+
+	if (set_is_interval(ctx->set->flags) &&
+	    !(ctx->set->flags & NFT_SET_CONCAT) &&
+	    interval_set_eval(ctx, ctx->set, set->init) < 0)
+		return -1;
+
+	ctx->set = NULL;
+
+	return 0;
+}
+
 static int set_evaluate(struct eval_ctx *ctx, struct set *set)
 {
 	struct set *existing_set = NULL;
@@ -4461,23 +4484,6 @@ static int set_evaluate(struct eval_ctx *ctx, struct set *set)
 	}
 
 	set->existing_set = existing_set;
-	ctx->set = set;
-	if (set->init != NULL) {
-		__expr_set_context(&ctx->ectx, set->key->dtype,
-				   set->key->byteorder, set->key->len, 0);
-		if (expr_evaluate(ctx, &set->init) < 0)
-			return -1;
-		if (set->init->etype != EXPR_SET)
-			return expr_error(ctx->msgs, set->init, "Set %s: Unexpected initial type %s, missing { }?",
-					  set->handle.set.name, expr_name(set->init));
-	}
-
-	if (set_is_interval(ctx->set->flags) &&
-	    !(ctx->set->flags & NFT_SET_CONCAT) &&
-	    interval_set_eval(ctx, ctx->set, set->init) < 0)
-		return -1;
-
-	ctx->set = NULL;
 
 	return 0;
 }
@@ -4940,6 +4946,8 @@ static int cmd_evaluate_add(struct eval_ctx *ctx, struct cmd *cmd)
 	case CMD_OBJ_SET:
 		handle_merge(&cmd->set->handle, &cmd->handle);
 		return set_evaluate(ctx, cmd->set);
+	case CMD_OBJ_SETELEMS:
+		return elems_evaluate(ctx, cmd->set);
 	case CMD_OBJ_RULE:
 		handle_merge(&cmd->rule->handle, &cmd->handle);
 		return rule_evaluate(ctx, cmd->rule, cmd->op);
diff --git a/src/libnftables.c b/src/libnftables.c
index 8537d700..b74429d5 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -547,13 +547,6 @@ static int nft_evaluate(struct nft_ctx *nft, struct list_head *msgs,
 	if (err < 0 || nft->state->nerrs)
 		return -1;
 
-	list_for_each_entry(cmd, cmds, list) {
-		if (cmd->op != CMD_ADD)
-			continue;
-
-		nft_cmd_post_expand(cmd);
-	}
-
 	return 0;
 }
 
diff --git a/src/rule.c b/src/rule.c
index 88bd5656..c4cdfa66 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -1396,21 +1396,6 @@ void nft_cmd_expand(struct cmd *cmd)
 		nft_cmd_expand_chain(chain, &new_cmds);
 		list_splice(&new_cmds, &cmd->list);
 		break;
-	default:
-		break;
-	}
-}
-
-void nft_cmd_post_expand(struct cmd *cmd)
-{
-	struct list_head new_cmds;
-	struct set *set;
-	struct cmd *new;
-	struct handle h;
-
-	init_list_head(&new_cmds);
-
-	switch (cmd->obj) {
 	case CMD_OBJ_SET:
 	case CMD_OBJ_MAP:
 		set = cmd->set;
@@ -1641,7 +1626,13 @@ static int do_add_set(struct netlink_ctx *ctx, struct cmd *cmd,
 			return -1;
 	}
 
-	return mnl_nft_set_add(ctx, cmd, flags);
+	if (mnl_nft_set_add(ctx, cmd, flags) < 0)
+		return -1;
+
+	if (set_is_anonymous(set->flags))
+		return __do_add_elements(ctx, cmd, set, set->init, flags);
+
+	return 0;
 }
 
 static int do_command_add(struct netlink_ctx *ctx, struct cmd *cmd, bool excl)